Pancreatic ducts of the rat and hamster will be isolated and cultured for six to eight weeks in an agarose matrix in CMRL-1066 supplemented with fetal bovine serum, insulin, and dexamethasone. The ducts will be exposed to benzo(a)pyrene, 7,12-dimethylbenzanthracene, and N-nitroso-bis(2-oxopropyl)amine in an effort to cause histologic changes similar to those seen in the pancreas in vivo. The effects of these carcinogens will be potentiated by exposure in the presence of liver microsomes, the use of younger animals with larger proportions of mitotically active cells, and by the addition of growth and tumor promoters such as phorbol esters to the growth medium. The effects of the carcinogens will be monitored morphologically with light and electron microscopes, biochemically by enzyme assays and SDS-polyacrylamide gel electrophoresis, and biologically by assessing the ability of the treated cells to form colonies in soft agar and to grow in a host animal.